1. Field of the Invention
The present invention relates to a liquid processing apparatus for performing a predetermined liquid process on a substrate, such as a semiconductor wafer. For example, this liquid process is a cleaning process for removing particles and/or contaminants deposited on a semiconductor wafer.
2. Description of the Related Art
In the process of manufacturing semiconductor devices or flat panel display devices (FPD), liquid processes are frequently used, in which a process liquid is supplied onto a target substrate, such as a semiconductor wafer or glass substrate. For example, processes of this kind encompass a cleaning process for removing particles and/or contaminants deposited on a substrate, and a coating process for applying a photo-resist liquid or development liquid in a photolithography stage.
As a liquid processing apparatus used for this purpose, the following apparatus is known. Specifically, a substrate, such as a semiconductor wafer, is held on a spin chuck, and a process liquid is supplied onto the front surface or front and back surfaces of the wafer, while the wafer is rotated. Consequently, a liquid film is formed on the front surface or front and back surfaces of the wafer, thereby performing a process.
In general, an apparatus of this kind is arranged to supply a process liquid onto the center of a wafer, and rotate the wafer to spread the process liquid outward, thereby forming a liquid film and throwing off the process liquid. A surrounding member, such as a cup, is disposed around the wafer to guide downward the process liquid thrown off from the wafer, so that the process liquid is swiftly drained. However, where a cup or the like is used, part of the process liquid may bounce back to the wafer as mist, and generate defects thereon, such as water marks and/or particles.
As a technique for preventing this problem, Jpn. Pat. Appln. KOKAI Publication No. 8-1064 discloses a technique which utilizes a process liquid receiving member to be rotated integratedly with rotary support means that rotates along with a substrate held thereon in a horizontal state. The process liquid receiving member receives a process liquid scattered around the substrate, and guides the process liquid outward to collect it.
According to this technique, the process liquid receiving member rotatable along with the substrate is disposed adjacent to the peripheral portion of the substrate. This arrangement is conceived to reliably collect the process liquid scattered around the substrate and to prevent the liquid from being re-deposited on the substrate.
However, even if the technique disclosed in Jpn. Pat. Appln. KOKAI Publication No. 8-1064 is adopted, the process may be adversely affected by mist to some extent. Particularly, in the case of a cleaning process, problems tend to arise during the ending period of a drying step after a cleaning step, such that drying becomes insufficient due to re-deposition of small droplets of mist and locally promoted vaporization of isopropyl alcohol (IPA) used for the drying step.